| 发表于：2007-06-17 16:29:04 楼主 |
下面是一个钟表程序的一部分，模拟秒针旋转所以要旋转位图。在ontimer里有内存泄露，ontimer每秒执行一次，能看到内存明显增长。可能是旋转位图引起的，请各位大虾看看如何改正。thanks。
//几个成员变量：
cdc m_dcsecpointer;//the second pointer
cpoint m_clockcenter;//the clock pointer center
cdc m_dcbkground;//the back ground
//ontimer函数，里面调用了rotatebitmap（）函数
void cclockdlg::ontimer（uint nidevent)
{
ctime time=ctime::getcurrenttime（);
int nsec=time.getsecond（);
float fangle;
cpoint points;
hdc dcs;
int nws=sec_width;
int nhs=sec_height;
switch（nidevent)
{
case main_timer:
fangle=nsec*6*pi/180;
points.y=-sec_height*cos（fangle)/2;
points.x=sec_height*sin（fangle)/2;
points=points+m_clockcenter;
dcs=rotatebitmap（m_dcsecpointer,nws,nhs,points,fangle);
getdc（)-> stretchblt（0,0,m_clockcenter.x*2,2*m_clockcenter.y,&m_dcbkground,0,0,m_clockcenter.x*2,2*m_clockcenter.y,srccopy);
transparentblt（getdc（)-> m_hdc,points.x,points.y,nws,nhs,dcs,0,0,nws,nhs,rgb（0,0,0));
deletedc（dcs);
break;
}
cdialog::ontimer（nidevent);
}
//旋转位图的函数
hdc cclockdlg::rotatebitmap（
hdc dcsrc,//source bitmap
int &srcwidth,
//[in]width of source bitmap
//[out]width of the rotated bitmap
int &srcheight,
//[in]height of source bitmap
//[out]height of the rotated bitmap
cpoint &cpcenter,
//[in]the rotated bitmap 's center wanted be shown
//[out]the rotated bitmap 's left top corner
double dangle//angle of rotation and y axis
)
{//return value:rotated bitmap is temporarily stored here
double x1,x2,x3,y1,y2,y3;
double maxwidth,maxheight,minwidth,minheight;
double srcx,srcy;
double sina,cosa;
double dstwidth,dstheight;
hdc tmpdcdst;//temp dc for rotate
hbitmap newbitmap;
sina = sin（dangle);
cosa = cos（dangle);
x1 = -srcheight * sina;
y1 = srcheight * cosa;
x2 = srcwidth * cosa - srcheight * sina;
y2 = srcheight * cosa + srcwidth * sina;
x3 = srcwidth * cosa;
y3 = srcwidth * sina;
minwidth = x3> （x1> x2?x2:x1)?（x1> x2?x2:x1):x3;
minwidth = minwidth> 0?0:minwidth;
minheight = y3> （y1> y2?y2:y1)?（y1> y2?y2:y1):y3;
minheight = minheight> 0?0:minheight;
maxwidth = x3> （x1> x2?x1:x2)?x3:（x1> x2?x1:x2);
maxwidth = maxwidth> 0?maxwidth:0;
maxheight = y3> （y1> y2?y1:y2)?y3:（y1> y2?y1:y2);
maxheight = maxheight> 0?maxheight:0;
dstwidth = maxwidth - minwidth;
dstheight = maxheight - minheight;
//prepare a temp empty bitmap for drawing
tmpdcdst = createcompatibledc（dcsrc);
newbitmap = createcompatiblebitmap（dcsrc,（int)dstwidth,（int)dstheight);
selectobject（tmpdcdst,newbitmap);
//copy to the temp bitmap from source bitmap
for（ int i = 0 ;i <dstheight;i++){
for（int j = 0 ;j <dstwidth;j++){
srcx = （j + minwidth) * cosa + （i + minheight) * sina;
srcy = （i + minheight) * cosa - （j + minwidth) * sina;
if（ （srcx > = 0) && （srcx <= srcwidth) &&（srcy > = 0) && （srcy <= srcheight))
{
bitblt（tmpdcdst, j, i, 1, 1, dcsrc,（int)srcx, （int)srcy, srcinvert);
}
}
}
deleteobject（newbitmap);
//return values
srcwidth=dstwidth;
srcheight=dstheight;
cpcenter.x=cpcenter.x-dstwidth/2;
cpcenter.y=cpcenter.y-dstheight/2;
return tmpdcdst;
} |
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